Scientists worry whether Russia's 'Sputnik V' coronavirus vaccine is safe and effective

• Scientists are skeptical about Putin's claims on Russia's potential Covid-19 vaccine, saying the vaccine still needs critical data to determine whether it's safe or effective.
• Developing, testing and reviewing any potential vaccine is a long, complex and expensive endeavor that typically takes months or even years.
• "Phase three trials are critical" for vaccine development, said Daniel Salmon, director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health.

Scientists and public health officials are skeptical about Russian President Vladimir Putin's claim that the country's potential vaccine for the coronavirus "works quite effectively," saying Tuesday that the vaccine still needs critical testing to determine whether it's safe and effective. 

Hours earlier, Putin said Russian health officials approved what he said is the first coronavirus vaccine in the world, adding that one of his daughters has already taken it. Clinical trials of the vaccine have been completed in less than two months and phase three trials are set to begin on Wednesday, even as Russia lays out plans for a "massive release" to the public. Russian officials say they hope to soon start immunizing people with the vaccine, which, according to The Wall Street Journal, they've dubbed Sputnik V, named for the world's first satellite, launched in 1957.

"As far as I know, a vaccine against a new coronavirus infection has been registered this morning, for the first time in the world," Putin said at a meeting with members of the government, RIA Novosti reported. "Although I know that it works quite effectively, it forms a stable immunity and, I repeat, has passed all the necessary checks," Putin said. Russia's health minister has previously said it plans to roll the vaccine out for public use in October, the Journal reported. 

Not confident 

However, medical experts warn that without a large-scale phase three clinical trial, it's really unknown whether the vaccine even works and what potential side effects it could have on the general public.

"Phase three trials are critical" for drug and vaccine development, said Daniel Salmon, director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health. "Would I be confident about the safety and effectiveness without a phase three? Absolutely not." 

Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia, said he worries Russia's vaccine approval could pressure the U.S. to deploy a vaccine before it's ready.

"It could be a major mistake. It could cause a lot of harm," he told CNBC's "The Exchange," adding Russia's move was a "political stunt."

The World Health Organization has said there is no "silver bullet" for the coronavirus, which has infected more than 20 million people worldwide and killed at least 737,000 as of Tuesday, according to data compiled by Johns Hopkins University. Scientists across the globe are racing to develop a safe and effective vaccine for the virus in record time.

There are more than 150 vaccines under development worldwide, including Russia's, according to the WHO, with 26 already in human trials.

Tough hurdles

The vaccine also appears to face a tough hurdle winning approval from the WHO before the international health organization will buy or recommend it to other nations.

"You cannot use a vaccine or drugs or medicines without following through all of these stages, having complied with all of these stages," Dr. Jarbas Barbosa, assistant director of WHO's Pan American Health Organization, said at a press conference Tuesday. "Currently WHO is in contact with the regulatory authorities in Russia in order to receive information on this vaccine and only after analyzing all of the information making it possible for WHO to make a recommendation." 

Developing, testing and reviewing any potential vaccine is a long, complex and expensive endeavor that typically takes months or even years. The fastest-ever vaccine development, for mumps, took more than four years before it was licensed in 1967. 

Effects on the human body

Additionally, scientists caution that questions remain about the short- and long-term effects of the coronavirus on the human body. It was only discovered seven months ago and it hasn't been studied in depth, they say. 

To be sure, Russia has "phenomenal" scientists and is a powerhouse when it comes to many aspects of science, said infectious disease specialist Isaac Bogoch. Although he has "no doubts" Russia can create a safe and effective vaccine, Bogoch said he was still skeptical.

"You can't just start giving a vaccine to the public," said Bogoch, a professor at the University of Toronto.  

Scientists at Moscow's Gamaleya Institute for Epidemiology and Microbiology used military-style testing, sped up clinical evaluations and took other measures to shorten the time needed to develop and review the vaccine, the Journal reported. 

Transparent data

The shortened review also made U.S. Health and Human Services Secretary Alex Azar wary.

"We need transparent data, and it's got to be phase three data that shows that a vaccine is safe and effective," he said in an interview on ABC on Tuesday. "The point is not to be first with a vaccine, the point is to have a vaccine that is safe and effective for the American people and the people of the world."

Early stage trials are small, typically testing a drug or vaccine on 20 to 80 healthy volunteers. Phase three trials, which typically randomize who gets the vaccine and who doesn't, can have thousands of participants from different backgrounds and are needed to root out any potential side effects, medical experts say. Drug companies Pfizer and Moderna last month both began late-stage trials for potential coronavirus vaccines, which are both expected to include up to 30,000 participants. 

Randomized trial needed

"The randomization process is critical. There are things you do know, like underlying health status. But then there are things that you don't know that could be a factor, like genetics," Salmon said. "When you randomize the process, it takes care of that. You have a really good comparison group."

"If five people have a heart attack in one group, you can compare it to the other group," he added. "Once a vaccine is licensed and used, it's harder to study because it's not randomized."

Dr. Scott Gottlieb, a former U.S. Food and Drug Administration commissioner, urged caution about Russia's coronavirus vaccine, telling CNBC on Tuesday he would "certainly not" take it outside of a clinical trial where patients are closely monitored.

Questions about safety

"They're claiming that it's fully approved, but it's not fully approved," said Gottlieb, who also sits on Pfizer's board. 

Researchers have yet to publish any data on the vaccine trials thus far, including information on the safety, efficacy or possible long-term side effects. Gottlieb said that wouldn't fly with American regulators.

"We certainly wouldn't allow a vaccine to be used for mass distribution at this point based on the data we have at hand," he said. "We just don't know if the vaccines are safe and effective at this point." 

Russia's sovereign wealth fund, the Russian Direct Investment Fund, said Tuesday that it's backing the production of the vaccine for sale in foreign markets. It said there had been "considerable interest" from abroad.

— CNBC's Noah Higgins-Dunn, Holly Ellyatt and Kevin Stankiewicz contributed to this report.